Factors that influence exhaled nitric oxide in Italian schoolchildren.
BACKGROUND
Conflicting results exist about the meaning of exhaled nitric oxide (eNO) in epidemiologic studies, mainly because of the numerous factors that may affect the measurement.


OBJECTIVE
To evaluate the role of the factors that influence eNO levels in a sample of schoolchildren with or without respiratory diseases. We studied 335 schoolchildren, ages 10 to 16 years, from 8 schools in Palermo, Italy. After a respiratory questionnaire was completed, spirometry, skin tests, and eNO measurements were performed.


RESULTS
Among 335 children, 13.7% reported symptoms of bronchial asthma, 46.9% reported symptoms of rhinitis, and 39.4% were asymptomatic. The ratio of forced expiratory volume in 1 second to forced vital capacity was 87.6% (SD, 6.4%) in the bronchial asthma group, 90.6% (SD, 5.0%) in the rhinitis group, and 90.4% (SD, 5.1%) in the asymptomatic group (P < .002). Atopic children constituted 52.2% of the bronchial asthma group, 40.1% of the rhinitis group, and 28.8% of the asymptomatic group. Among atopic children, 102 (82%) had a positive skin test result for Dermatophagoides. Median eNO was 12.6 ppb in nonatopic children and 21.2 ppb in atopic children (P < .001, by Mann-Whitney U test). Among asymptomatic children, atopic children had significantly higher eNO levels than did nonatopic children (P < .001). In nonatopic children, no difference was found in log transformation eNO among healthy, rhinitic, or asthmatic children. Log transformation eNO increased with the number of positive skin test results (P < .001). Atopy, asthma, male sex, and indoor allergens were predictors of increased eNO in a logistic model.


CONCLUSIONS
Atopy (in particular, sensitization to indoor and perennial allergens) is strongly associated with higher eNO levels. Such association is enhanced by asthma.
Cibella
Fabio
F
Consiglio Nazionale delle Ricerche, Istituto di Biomedicina e Immunologia Molecolare, Palermo, Italy. cibella@ibim.cnr.it
Cuttitta
Giuseppina
G
La Grutta
Stefania
S
Passalacqua
Giovanni
G
Viegi
Giovanni
G
D000293:Adolescent; D000485:Allergens / Q000276:immunology*; D001249:Asthma / Q000453:epidemiology* / Q000276:immunology; D001944:Breath Tests; D002648:Child; D003430:Cross-Sectional Studies; D045853:Exhalation; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000453:epidemiology* / Q000276:immunology; D007558:Italy / Q000453:epidemiology; D008297:Male; D009569:Nitric Oxide / Q000032:analysis*; D012220:Rhinitis / Q000453:epidemiology* / Q000276:immunology; D012737:Sex Factors; D012882:Skin Tests; D013147:Spirometry
D000485:Allergens; D009569:Nitric Oxide